Impact of Intraocular Lens Haptic Design and Orientation

8/3/2019 Impact of Intraocular Lens Haptic Design and Orientation

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Impact of intraocular lens

haptic design andorientation on

decentration and tilt


2/19

Pendahuluan

Cataract surgery has transitioned from being atreatment for visual rehabilitation to also beinga refractive procedure with aim of gaining visual

function comparable to non cataract elderly eye

Aspheric IOL compensate for sphericalabberation of cornea and contrast sensitivity


3/19

Multifocal IOL decrease spectacledependence

Toric Iolcorrect corneal astigmatism and uncorrected distance vision

IOL performance highly depends on theposition of IOL in the optical system

Holladay et al asperic IOL should bedecentered < 0.4 mm and tilted < 7


4/19

Piers et al critical decentration 0.8 mm and 10 as critical tilt point

Decentration and tilt can be assessed with slitlamp,retroillumination photography, Scheimpflugimaging, and Purkinje reflections.

Purkinje images provide qualitative informationabout IOL alignment and more accurate thanScheimpflug imaging

The aim of this study: to compared the effet of IOLhaptic orientation and haptic-loop design on IOLcentration and tilt using a Purkinje meter.


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Patients and method

Prospective randomized study with intraindividualcomparison comprised patient with age-relatedcataract

Exclusion criteria:- age < 21 years old

- pseudoexfoliation syndrome

- pigment dispersion syndrome- history of ocular trauma or other ocularcomorbiditythat could affect IOLs position


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method

Study consisted of 2 parts

Part 1 comparation of tilt and decentrationbetween horizontal and vertical orientation of aplate-style IOL

One eye was oriented with its haptic horizontalor vertical orientation according randomization,and contralateral eye get the alternate orientation


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Part 2 comparation between hydrophobicacrylic 1-piece IOL with the same hapticmaterial and 3-piece IOL with PMMA haptic

One eye get a 1-piece openloop or a 3-pieceopen-loop IOL according to randomization,contralateral eye get the alternate IOL hapticdesign

both of them were vertically oriented andcentered on the pupil


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Postop evaluation are 1 month and 3 monthpostoperative

Recorded variables:

- visual acuity

- Purkinje meter images


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Results

30 patients were recruited

Mean age of 15 patients in part 1: 75 years

Mean age of 15 patients in part 2: 77 years Mean IOL power: 21.5 D (part 1) and 21.6 D

(part 2)


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Decentration & tilt at 3 month follow up (part 1):- nasal decentration: vertical 8 (57%)

horizontal 11 (77%)

- upward decentration: vertical

12 (79%)horizontal all- temporal tilted : vertical 12 (79%)

horizontal 9 (62%)

- downward tilted: all IOLs


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Decentration & tilt at 3 month follow up (part 2)

- nasal decentration: 1 piece IOL 10 (67%)

3 piece IOL 10 (67%)- upward decentration was measured in most IOLs inboth group,2 IOLs in each group decenterd

downward- temporal tilted: 1 piece IOL7 (45%)

3 piece IOL 8 (57%)

- downward tilted: most of IOLs; 1 IOL in 1-pieceand 2 IOLs in 3-piece group were tilted upward

- no statistically significant about differrences indecentration and tilt between 2 groups IOL


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Discussion

The first study to compare IOL axis orientationand to use Purkinje meter

The patient numbers may have been too small

to detect the effect of small or less relevantdifferences between the groups

In part 1 tendency toward nasal and upward

decentration on both groups & horizontaloriented IOL to decenter upward,especially at 3-months fu


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Because these findings, the IOL implant in part 2 wasoriented vertically

In part 2 most IOLs were tilted downward & slightlynasal

De Castro et al mostly nasal & upward decentration& nasally tilted

Mester et al:- 1-piece IOLnasal decentration & almost no vertical

displacement- crystalline lens temporal & downward displaced- both significantly up & temporal tilted


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Schaefel: temporal & inferior decentration; andsignificantly upward & temporal tilt

This study is slightly different with previous study

( Mester et al & Schaefel) in image acquisition andimage-analysis algorithm

Taketani et aldidnt find differences indecentration between 1-piece & 3-piece acrylic IOL

But the Scheimpflug imaging showed statisticallysignificant difference , where 3-piece tilted more


17/19

Hayashi et aldidnt find differences betweendecenration & tilt of 1-piece & 3-piece PMMAIOLs using anterior eye segment analysis

3-piece IOLs have tendencey to decenter & tiltmore than 1-piece IOL

The reason :- production process of 3-piece IOLs, where duringthe PMMA haptic are placed into optic with handthan machine- because the haptic is PMMA, which is known tolose its memory within few days under compresion- haptic may be deformed during implantationprocedure, causing slight kinking of the haptic


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In this study:

- minimize the mechanical stress on haptics byenlarging wound in cases of high powered IOLwith greater optic thickness & not maneuveringIOL by touching / grasping haptic with forceps

- the IOL were position on the bag by pushingon the optic


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conclusion

Axis orientation of a plate-haptic IOL in the bagseemed to have no clinical impact because thereis no differences in decentration and tilt in this

study

Single-piece IOL maybe more predictable thanmultipiece IOLs in terms of tilt and

decentration confirm with a larger trial

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Impact of Intraocular Lens Haptic Design and Orientation